Properties of Mechanically Alloyed W-Ti Materials with Dual Phase Particle Dispersion

František Lukáč,Orsolya Molnárová,Monika Vilémová,Barbara Nevrlá,Jakub Klečka,Tomáš Chráska

doi:10.3390/met7010003

Abstract

W alloys are currently widely studied materials for their potential application in future fusion reactors. In the presented study, we report on the preparation and properties of mechanically alloyed W-Ti powders compacted by pulsed electric current sintering. Four different powder compositions of W-(3%–7%)Ti with Hf or HfC were prepared. The alloys’ structure contains only high-melting-point phases, namely the W-Ti matrix, complex carbide (Ti,W,Hf)C and HfO2 particle dispersion; Ti in the form of a separate phase is not present. The bending strength of the alloys depends on the amount of Ti added. The addition of 3 wt. % Ti led to an increase whereas 7 wt. % Ti led to a major decrease in strength when compared to unalloyed tungsten sintered at similar conditions. The addition of Ti significantly lowered the room-temperature thermal conductivity of all prepared materials. However, unlike pure tungsten, the conductivity of the prepared alloys increased with the temperature. Thus, the thermal conductivity of the alloys at 1300 °C approached the value of the unalloyed tungsten.

Highlights

With the progress of nuclear fusion research, the need for new, advanced materials is becoming more urgent
The lattice parameters were significantly larger than the lattice parameter of pure tungsten at room temperature a = 0.3165 nm [8]
Ti and Hf was transformed into the complex carbide phase

Summary

Introduction

With the progress of nuclear fusion research, the need for new, advanced materials is becoming more urgent. For the International Thermonuclear Experimental Reactor (ITER), the choice of materials has been made. The area of the ITER’s first wall will be covered by armor produced from beryllium and the exhaust components will be covered by tungsten. Materials for the step of reactors will have to satisfy strict requirements for the lifetime and safety levels. Nontoxic, highly durable and functional materials would be the prime choice for tokamak such as DEMO tokamak. Pure tungsten was considered the most suitable plasma-facing material for the future reactor’s first wall. In the conditions of fusion plasma and plasma disruptions, excessive grain growth leads to the degradation of mechanical properties, which subsequently causes premature failure of the plasma-facing component during heat cycling

Methods

Results

Discussion

Conclusion